// ============================================================================
//
// Copyright (C) 2006-2019 Talend Inc. - www.talend.com
//
// This source code is available under agreement available at
// %InstallDIR%\features\org.talend.rcp.branding.%PRODUCTNAME%\%PRODUCTNAME%license.txt
//
// You should have received a copy of the agreement
// along with this program; if not, write to Talend SA
// 9 rue Pages 92150 Suresnes, France
//
// ============================================================================
package org.talend.designer.esb.runcontainer.preferences;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

import org.eclipse.jface.preference.FieldEditor;
import org.eclipse.jface.preference.PreferencePage;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.jface.util.IPropertyChangeListener;
import org.eclipse.jface.util.PropertyChangeEvent;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;

/**
 * A special abstract preference page to host field editors and eny other controls with flexible layout.
 */
public abstract class FieldLayoutPreferencePage extends PreferencePage implements IPropertyChangeListener {

    /**
     * The field editors.
     */
    private List<FieldEditor> m_fields = new ArrayList<FieldEditor>();

    /**
     * The first invalid field editor, or <code>null</code> if all field editors are valid.
     */
    private FieldEditor m_invalidFieldEditor;

    // //////////////////////////////////////////////////////////////////////////
    //
    // Constructors
    //
    // //////////////////////////////////////////////////////////////////////////
    /**
     * Creates a new field editor preference page with an empty title, and no image.
     */
    protected FieldLayoutPreferencePage() {
        // Create a new field editor preference page with an empty title, and no image
    }

    /**
     * Creates a new field editor preference page with the given title, but no image.
     *
     * @param title the title of this preference page
     */
    protected FieldLayoutPreferencePage(String title) {
        super(title);
    }

    /**
     * Creates a new field editor preference page with the given image, and style.
     *
     * @param title the title of this preference page
     * @param image the image for this preference page, or <code>null</code> if none
     */
    protected FieldLayoutPreferencePage(String title, ImageDescriptor image) {
        super(title, image);
    }

    // //////////////////////////////////////////////////////////////////////////
    //
    // Fields
    //
    // //////////////////////////////////////////////////////////////////////////
    /**
     * Adds the given field editor to this page.
     *
     * @param editor the field editor
     */
    protected void addField(FieldEditor editor) {
        m_fields.add(editor);
    }

    /**
     * Recomputes the page's error state by calling <code>isValid</code> for every field editor.
     */
    protected void checkState() {
        boolean valid = true;
        m_invalidFieldEditor = null;
        // The state can only be set to true if all
        // field editors contain a valid value. So we must check them all
        if (m_fields != null) {
            int size = m_fields.size();
            for (int i = 0; i < size; i++) {
                FieldEditor editor = m_fields.get(i);
                valid = valid && editor.isValid();
                if (!valid) {
                    m_invalidFieldEditor = editor;
                    break;
                }
            }
        }
        setValid(true);
    }

    /*
     * (non-Javadoc) Method declared on PreferencePage.
     */
    @Override
    protected Control createContents(Composite parent) {
        Control contens = createPageContents(parent);
        initialize();
        checkState();
        return contens;
    }

    /**
     * Creates and returns the SWT control for the customized body of this preference page under the given parent
     * composite.
     * <p>
     * This framework method must be implemented by concrete subclasses. Any subclass returning a <code>Composite</code>
     * object whose <code>Layout</code> has default margins (for example, a <code>GridLayout</code>) are expected to set
     * the margins of this <code>Layout</code> to 0 pixels.
     * </p>
     *
     * @param parent the parent composite
     * @return the new control
     */
    protected abstract Control createPageContents(Composite parent);

    /**
     * The field editor preference page implementation of an <code>IDialogPage</code> method disposes of this page's
     * controls and images. Subclasses may override to release their own allocated SWT resources, but must call
     * <code>super.dispose</code>.
     */
    @Override
    public void dispose() {
        super.dispose();
        if (m_fields != null) {
            Iterator<FieldEditor> I = m_fields.iterator();
            while (I.hasNext()) {
                FieldEditor editor = I.next();
                editor.setPage(null);
                editor.setPropertyChangeListener(null);
                editor.setPreferenceStore(null);
            }
        }
    }

    /**
     * Initializes all field editors.
     */
    protected void initialize() {
        if (m_fields != null) {
            Iterator<FieldEditor> I = m_fields.iterator();
            while (I.hasNext()) {
                FieldEditor editor = I.next();
                editor.setPage(null);
                editor.setPropertyChangeListener(this);
                editor.setPreferenceStore(getPreferenceStore());
                editor.load();
            }
        }
    }

    /**
     * The field editor preference page implementation of a <code>PreferencePage</code> method loads all the field
     * editors with their default values.
     */
    @Override
    protected void performDefaults() {
        if (m_fields != null) {
            Iterator<FieldEditor> I = m_fields.iterator();
            while (I.hasNext()) {
                FieldEditor editor = I.next();
                editor.loadDefault();
            }
        }
        // Force a recalculation of my error state.
        checkState();
        super.performDefaults();
    }

    /**
     * The field editor preference page implementation of this <code>PreferencePage</code> method saves all field
     * editors by calling <code>FieldEditor.store</code>. Note that this method does not save the preference store
     * itself; it just stores the values back into the preference store.
     *
     * @see FieldEditor#store()
     */
    @Override
    public boolean performOk() {
        if (m_fields != null) {
            Iterator<FieldEditor> I = m_fields.iterator();
            while (I.hasNext()) {
                FieldEditor editor = I.next();
                editor.store();
            }
        }
        return true;
    }

    /**
     * The field editor preference page implementation of this <code>IPreferencePage</code> (and
     * <code>IPropertyChangeListener</code>) method intercepts <code>IS_VALID</code> events but passes other events on
     * to its superclass.
     */
    @Override
    public void propertyChange(PropertyChangeEvent event) {
        if (event.getProperty().equals(FieldEditor.IS_VALID)) {
            boolean newValue = ((Boolean) event.getNewValue()).booleanValue();
            // If the new value is true then we must check all field editors.
            // If it is false, then the page is invalid in any case.
            if (newValue) {
                checkState();
            } else {
                m_invalidFieldEditor = (FieldEditor) event.getSource();
                setValid(newValue);
            }
        }
    }

    /*
     * (non-Javadoc) Method declared on IDialog.
     */
    @Override
    public void setVisible(boolean visible) {
        super.setVisible(visible);
        if (visible && m_invalidFieldEditor != null) {
            m_invalidFieldEditor.setFocus();
        }
    }

    public List<FieldEditor> getFieldEditors() {
        return m_fields;
    }
}